The present invention refers to a throttle-valve connection having a throttle-valve shaft which can be actuated by an electric motor and mechanically by means of a setting lever.
Throttle-valve connections of this type are used in motor vehicles for adjusting the engine output power and are generally known. While formerly displacement of the throttle valve was effected exclusively mechanically via a pull cable upon movement of the accelerator pedal, modern motor vehicles contain control devices which, under given conditions of travel change the engine output power independently of the position of the accelerator pedal. When, as a result of too high an engine output, slippage of the driven wheels may take place on a slippery substrate, the throttle valve must, for instance, be swung in closing direction contrary to the driver's command. In idle operation, the throttle valve is frequently opened beyond the normal idle position so that a higher power requirement resulting, for instance, from a turning on of the air conditioner can be satisfied. In the case of an automatic speed control, the throttle valve must be capable of being displaced in both directions independently of the accelerator pedal.
In the throttle-valve connections known up to the present time, a clutch is provided between the setting lever and the electric motor, the clutch connecting the electric motor to the throttle-valve shaft upon a control action by the electric motor. Such a clutch results in additional structural expense and may give rise to a failure of the control. Furthermore, the time required until a control action takes effect is increased by the clutch since the clutch must first be closed prior to the displacement of the throttle-valve shaft by the motor.